In general, in manufacturing semiconductor devices, semiconductor wafers are repeatedly subjected to various processes such as deposition, oxidative diffusion, modification, etching, annealing and so on. In order to perform such various processes with efficiency, there has been known a so-called cluster tool type processing system as disclosed in Patent Document 1 (Japanese Patent Application Publication No. 2007-027378). In this processing system, a plurality of single wafer type process chambers is connected to a common transfer chamber under a vacuum atmosphere and semiconductor wafers are sequentially subjected to required processes while being transferred to the process chambers via the common transfer chamber.
In this case, one or more small capacity load lock devices capable of selectively implementing a vacuum atmosphere and an air atmosphere are connected to the common transfer chamber. In addition, in order to load/unload the semiconductor wafers between the common transfer chamber of the vacuum atmosphere and the outside of the air atmosphere, by selectively setting the load lock devices to the vacuum atmosphere or the air atmosphere, the semiconductor wafers can be loaded/unloaded without destroying the vacuum atmosphere of the common transfer chamber. Here, each of the load lock devices has a cooling mechanism such as a cooling plate or the like for cooling the semiconductor wafers, which are heated to a high temperature by various heat treatments in the process chambers, to a safe temperature, for example, about 100° C., and the semiconductor wafers are discharged to the outside after being cooled to 100° C. or below.
As other methods for cooling the semiconductor wafers, there have been proposed a method for cooling the semiconductor wafers by using down-flow formed in a transfer chamber of the air atmosphere (see, e.g., Patent Document 2: Japanese Patent Application Publication No. 2006-253683) and a method for installing a cooling station in a transfer chamber of the air atmosphere (see, e.g., Patent Document 3: Japanese Patent Application Publication No. 2005-518655). Further, as for the cooling mechanism of the semiconductor wafer, there have been proposed a technique for providing a cold plate arranged with cooling pipes, (see, e.g., Patent Document 4: a Japanese Patent Application Publication No. 2002-057092) and a technique for cooling central portions of wafers with efficiency by using convex adsorbing portions formed in a central portion of a cooling plate (see, e.g., Patent Document 5: Japanese Patent Application Publication No. 1999-330212).
However, in recent years, there has been proposed a processing system having only process chambers for processing semiconductor wafers in an air atmosphere not in a vacuum atmosphere for the purpose of simplification of the processing system. As used herein, the “air atmosphere” does not refer to an atmospheric pressure exactly but has the concept opposed to a decompressed vacuum atmosphere. In actuality, a pressure range of about ±0.01 Torr with respect to the atmospheric pressure is called “air atmosphere”. Examples of processes performed under such an air atmosphere may include annealing, oxidative diffusion, modification and so on.
When heat treatment is performed under the above-mentioned air atmosphere, the load lock devices for selectively implementing the vacuum atmosphere and the air atmosphere are unnecessary and the process chambers can be directly connected to the transfer chamber of the air atmosphere. In this case, in order to cool the wafers to a handling temperature, there is a need to separately provide the cooling mechanisms which would be provided in the load lock devices. However, the cooling mechanisms as disclosed in Patent Documents 2 to 4 are complicated. Therefore, there is a need of a cooling mechanism with a simpler structure.
In light of the above circumstances, it is an object of the present invention to provide a cooling mechanism capable of cooling a target object in an atmospheric transfer chamber with efficiency, and a processing system including the same.